Air Inlet and Exhaust System
SMCS - 1050 The engine components of the air inlet and exhaust system control the quality of air and the amount of air that is available for combustion. The components of the air inlet and exhaust system are the following components: • Air cleaner • Turbochargers • Precooler • Aftercooler (If equipped) • Cylinder head • Valves and valve system components • Piston and cylinder • Exhaust manifold • Clean Gas Induction (CGI) cooler • Diesel Particulate Filter (DPF) • Valve for the Combustion Air • Aftertreatment Regeneration Device (ARD) The low pressure turbocharger compressor wheel pulls the inlet air through the air cleaner and into the air inlet. The air is compressed by the low pressure turbocharger. Pressurizing the inlet air causes the air to heat up. The pressurized air exits the low pressure turbocharger through the outlet and the air is forced into the inlet of the high pressure turbocharger. The high pressure turbocharger is used in order to compress the air to a higher pressure. This increase in pressure continues to cause the inlet air's temperature to increase. As the air is

compressed, the air is forced through the high pressure turbocharger's outlet and into the air lines to the precooler. The pressurized inlet air is cooled by the precooler prior to being sent to the aftercooler. The precooler uses engine coolant to cool the air. Without the precooler, the inlet air would be too hot in order to be cooled sufficiently by the aftercooler. The inlet air then enters aftercooler core. The inlet air is cooled further by transferring heat to the ambient air. The combustion efficiency increases as the temperature of the inlet air decreases. Combustion efficiency helps to provide increased fuel efficiency and increased horsepower output. The aftercooler core is a separate cooler core that is mounted in front of the engine radiator. The engine fan and the ram effect of the forward motion of the vehicle causes ambient air to move across the core. Inlet air is forced from the aftercooler into the engine's intake manifold. The air flow from the intake manifold into the cylinders and out of the cylinders is controlled by engine's valve mechanisms. Each cylinder has two inlet valves and two exhaust valves that are mounted in the cylinder head. The inlet valves open when the piston moves downward on the inlet stroke. When the inlet valves open, cooled, compressed air from the intake manifold is pulled into the cylinder. The inlet valves close when the piston begins to move upward on the compression stroke. The air in the cylinder is compressed by the piston. As the air is compressed by the piston, the temperature of the air in the cylinder is heated. Fuel is injected into the cylinder when the piston is near the top of the compression stroke. Combustion begins when the fuel mixes with the hot, pressurized air. The force of combustion pushes the piston downward on the power stroke. The exhaust valves are opened as the piston travels upward to the top of the cylinder. The exhaust gases are pushed through the exhaust port into the exhaust manifold. After the piston completes the exhaust stroke, the exhaust valves close and the cycle begins again. Exhaust gases from the exhaust manifold flow into the high pressure turbocharger's exhaust inlet. The hot gases that are expelled from the engine are used to turn the turbine wheel of the turbocharger. The turbine wheel drives the compressor wheel that is used in order to compress the inlet air that enters the inlet side of the turbocharger. The exhaust gas exits from the high pressure turbocharger through the high pressure turbocharger's exhaust outlet. The wastegate is used by the high pressure turbocharger to prevent an overspeed condition of the turbocharger's turbine wheel during engine acceleration. The wastegate also prevents excessive boost of the engine during engine acceleration. The wastegate is controlled by the boost pressure that is felt in the air hose assembly that connects the inlet side of the two turbochargers. The wastegate pressure line provides the air pressure to the wastegate's diaphragm. As the diaphragm reacts to high boost pressure, a valve is actuated. The valve allows exhaust gas to bypass the high pressure turbocharger's turbine. This effectively controls the speed of the turbine. The exhaust gases then enter the exhaust inlet for the low pressure turbocharger. The exhaust gases drive the turbocharger's turbine. This energy is used in order to compress the inlet air in the same manner as the high pressure turbocharger. The exhaust gases then exit the low pressure turbocharger through the exhaust outlet for the low pressure turbocharger. The exhaust gases are then expelled into the vehicle's exhaust system.

Clean Gas Induction (CGI)
The CGI sends hot exhaust gas from the DPF to the CGI cooler. The hot exhaust gas is cooled in the CGI cooler. The now cooled exhaust gas passes through an electronic controlled flapper valve. The electronically controlled flapper valve is hydraulically actuated. The engine is using air from the truck's air filter system when the flapper valve is in the full OFF position. As the flapper valve starts to open the flow of cooled exhaust gas from the CGI cooler mixes with the air flow from the

air filter. As the demand for more cooled exhaust gas increases the flapper valve opens wider. This increases the flow of cooled exhaust gas from the CGI cooler. As the demand for more cooled exhaust gas increases, the demand for air flow from the engine's air filter decreases.

Diesel Particulate Filter (DPF)
The DPF and the Aftertreatment Regeneration Device (ARD) work together in order to reduce particulate emissions. The DPF collects the soot in the exhaust. The process of converting soot into gas is called regeneration. The ARD helps to accomplish this process when regeneration is required. Ash from the engine oil is also collected in the DPF. The DPF filters soot from the exhaust gas. If the temperature that is in the DPF is hot enough, the DPF converts the soot into gas. If the temperature that is in the DPF is not hot enough, the DPF retains the soot. When the soot must be removed from the DPF, the electronic control module will activate the ARD so that the soot can be oxidized into gas. Regeneration will be required more frequently when the engine is operated at extended idle and when the engine is operated in cold conditions. The DPF will need periodic cleaning of the accumulation of ash that occurs from the engine oil.

Valve for Combustion Air
The valve for the combustion air controls the amount of boosted air that is used by the ARD for optimal operation.

Aftertreatment Regeneration Device (ARD)
The temperature of the DPF must be above a particular value in order for regeneration to occur. The exhaust gas provides heat for the regeneration process. There are two types of regeneration: Passive Regeneration - The engine provides sufficient exhaust gas temperature for regeneration. Active Regeneration - The engine's duty cycle does not provide sufficient exhaust temperature for passive regeneration. The ARD operates in order to raise the temperature of the exhaust gas. When the regeneration process is complete, the ARD turns off.

. The valve is deenergized when the ARD is off. Air purge screw (11) allows air to be removed from the system during priming. 689 kPa (100 psi) regulator (14) provides a return path for the fuel to the fuel tank (34) if secondary fuel filter (10) becomes restricted. Bypass (8) ensures that the hand priming pump pulls fuel from the dirty side of secondary fuel filter (10). Secondary fuel filter (10) is a two micron filter. Primary fuel filter (33) is a ten micron filter.com/sisweb/sisweb/techdoc/techdoc_print_page.C15 On-highway Engine SDP00001-UP(SEBP4419 . Fuel at approximately 552 kPa (80 psi) is supplied to the cylinder head. ARD fuel enable valve (13) is controlled by the ECM. The operation of the system with ARD turned Off Refer to Illustration 1. 1103 kPa (160 psi) regulator (5) is bypassed by the ARD fuel enable valve.jsp?returnurl=/sisweb/s. Passages inside the fuel filter base route the fuel between the components.39) . All of the fuel for the cylinder head and for the ARD passes through the primary fuel filter.. The vehicle's fuel tank (34) provides fuel for cylinder head (4) and ARD head (23). Fuel filter base (1) provides mounting locations for several components. Fuel temperature sensor (6) provides a signal to the ECM. Fuel pressure sensor (3A) or (3B) sends a signal to the ECM. The signal indicates the temperature of the fuel for the cylinder head. The fuel transfer pump develops a maximum pressure of approximately 552 kPa (80 psi). All of the fuel for the cylinder head passes through the secondary fuel filter. Fluid sampling valve (7) provides a port for taking fuel samples. Pressure regulator (17) is nonserviceable. Optional hand priming pump (9) provides a means for removing air from the system. The signal indicates the fuel pressure inside the cylinder head. 30/05/2011
. Operation with the ARD turned On
https://sis.cat. The fuel transfer pump contains a pressure regulator (17) that limits the pump's output pressure to approximately 2068 kPa (300 psi).Documentación
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Fuel Supply Refer to Illustration 1. Fuel transfer pump (16) pressurizes the fuel. This pressure is regulated by 517 kPa (75 psi) regulator (12).

C15 On-highway Engine SDP00001-UP(SEBP4419 .com/sisweb/sisweb/techdoc/techdoc_print_page. Differential Pressure Sensor .Tubing connects the venturi's pressure taps to a differential pressure sensor.39) .The differential pressure sensor produces an electrical signal that indicates the pressure drop across the venturi.The venturi is a restriction in the duct between the air pressure control valve and the head of the ARD.. 30/05/2011
. The system for the combustion air consists of the following groups: • Sensor group • Control Group Sensor Group The sensor group consists of these components: Venturi . Tubing . Two pressure taps on the venturi provide connection points for tubing.jsp?returnurl=/sisweb/s..cat.
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(38) Fuel return line from the cylinder head (39) Fuel outlet port to the fuel tank
Illustration 5 Left side of the C15 engine (2) Manifold for the fuel pressure sensor (3A) Fuel pressure sensor
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Combustion Air
The system for the combustion air routes pressurized air (boost) from the outlet of the turbocharger to the ARD.

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. During a regeneration. the ECM commands the spool to a position that results in the desired flow of combustion air. Movement of the spool allows combustion air to flow to the ARD. Wiring sends the PWM signal from the ECM to the control group.jsp?returnurl=/sisweb/s...Documentación
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Electrical wiring sends the signals from the sensor to the Engine Control Module (ECM).cat.com/sisweb/sisweb/techdoc/techdoc_print_page. • Cleaner is forced through the nozzle when cleaner is present in the fuel lines for the ARD. The pressurized air performs the following functions: • Carbon buildup on the nozzle is minimized. • Residual fuel is removed from the fuel lines for the ARD. The coil creates a magnetic field that is detected by the air pressure control valve.C15 On-highway Engine SDP00001-UP(SEBP4419 . Control Group The control group maintains the ratio of air to fuel. The ECM can command the spool to any position between the closed position and the fully open position. The ECM creates a pulse width modulated signal that indicates the amount of combustion air that is desired.The air pressure control valve uses pressurized engine oil to convert the coil's magnetic field to movement of a spool. Air Pressure Control Valve . The ECM uses the signal to determine the amount of combustion air that is flowing to the ARD. The control group consists of the following components: Coil .The coil receives the PWM signal from the ECM.
ARD Purge Air
The ARD purge air system produces pressurized air for the ARD.39) .
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Illustration 7 Typical view of the left side of the engine (27) ARD purge air pump (28) 40 micron filter (29) Check valve (30) Cleaning port (31) Line for the air purge to the ARD (35) Electrical connector for the operating command from the ECM (36) Electrical connector for the battery power
https://sis.39) .C15 On-highway Engine SDP00001-UP(SEBP4419 .com/sisweb/sisweb/techdoc/techdoc_print_page..

Check Valve (29) . The check valve prevents fuel or cleaner from entering the ARD purge air system. The other part of the pump contains the moving components.com/sisweb/sisweb/techdoc/techdoc_print_page.The ARD purge air pump receives filtered air from the vehicle's air cleaner. The pump compresses the air.
https://sis. One part of the pump contains the electrical components. Lines route the air to the ARD head via a filter and a check valve. The pump consists of two parts.Documentación
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Illustration 8 Typical manifold for the lines to the ARD head (21) Manifold for the lines to the ARD (23) ARD head (31) Line for the purge air to the ARD head (32) Wire mesh filter
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ARD Purge Air Pump (27) . • The keyswitch is turned Off during an active regeneration. Operation The pump operates after the following conditions occur: • The keyswitch is turned On.C15 On-highway Engine SDP00001-UP(SEBP4419 .39) ..The check valve allows the purge air to flow to the ARD head.cat. The part that contains the moving components can be serviced separately.The 40 micron filter cleans the compressed air. Filter (28) .. 30/05/2011
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The pump receives electrical power from the vehicle's battery. The pump turns on and the pump turns off periodically.jsp?returnurl=/sisweb/s. • The ARD fails to ignite. A code is activated if the following conditions are true: • The pilot pressure is significantly different from the main pressure while the nozzle is being purged.C15 On-highway Engine SDP00001-UP(SEBP4419 . The ECM de-energizes solenoids (19) and (24) after the residual fuel has returned to the fuel tank. Purging the Nozzle The ECM does not energize solenoids (19) and (24) during this part of the purge process. This allows fuel and pressurized air to flow through the solenoids.
https://sis. The command completely opens the solenoids. The purge process has two parts.Documentación
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• An active regeneration is completed. The cleaner must be introduced for the following reasons: • The ARD purge air system has become inoperative. The system pressure is approximately 75 kPa (11 psi) during this part of the purge process. The pressurized air forces residual fuel to return to fuel tank (34) via de-energized ARD fuel enable valve (13). The circuit is protected by a fuse or by a circuit breaker.39) . The operating speed is determined by the electronics inside the pump. The pump operates at two speeds. 30/05/2011
. The ECM turns off the ARD purge air pump when the purge process is complete. This is normal operation. This is normal operation... The command turns on the pump. The ECM monitors the signal from pressure sensors (20) and (25) as the nozzle is purged. The ECM sends a command to the pump. The ECM monitors the signal from pressure sensors (20) and (25) as the lines are purged. • According to the maintenance schedule in the engine's Operation and Maintenance Manual Purging Residual Fuel From the Fuel Lines for the ARD The ECM sends a command to solenoids (19) and (24). The system pressure is approximately 280 kPa (40 psi) during this part of the purge process. The following information describes each part of the purge process. Cleaner is introduced into cleaning port (29) in order to clean the nozzle. The sound of the pump will change as the pump operates at the different speeds. • A "loss of combustion" event occurs. The pump operates for a period of time that is determined by the flash file in the ECM.com/sisweb/sisweb/techdoc/techdoc_print_page. The pressurized air flows through the nozzle in ARD head (23). Pressurized air flows through filter (28) and check valve (29).cat. The solenoids are closed. The pressurized air cannot flow past de-energized solenoids (19) and (24). Refer to Illustration 8.

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..jsp?returnurl=/sisweb/s.. This minimizes the buildup of carbon on the nozzle. The ARD combustion head contains an electric heating element. The nozzles inject pilot fuel and main fuel into the ARD for combustion. The nozzles can become plugged with carbon or with debris. Pump Operation During Engine Operation The pump runs continuously during normal engine operation. The Engine Control Module (ECM) periodically tests the condition of the nozzles. These conditions indicate that one of the check valves inside the ARD head is stuck in the closed position.39) .C15 On-highway Engine SDP00001-UP(SEBP4419 .
Heated Nozzle
There are two nozzles inside the ARD combustion head.Documentación
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• The pilot pressure is approximately equal to the main pressure while the lines are being purged.
https://sis.com/sisweb/sisweb/techdoc/techdoc_print_page.cat. The heating element operates periodically in order to clean the nozzles. The pump is turned off during an active regeneration.

The deactivated relay creates an open circuit for the electrical power to the heating element.jsp?returnurl=/sisweb/s.C15 On-highway Engine SDP00001-UP(SEBP4419 .cat.39) .. The activated relay creates a complete path for electrical power to the heating element.
Ignition
The ECM commands the spark plug to fire approximately 12 times each second whenever the keyswitch is ON and the engine speed is greater than 500 rpm. The relay is electronic. A 3530-31 code is active when the spark is disabled. This only applies if the "Disable" switch is off.
Refer to Illustration 12. The spark can be disabled via the "Disable" switch (if equipped) in the cab or by the "ARD Manual Disable Status" parameter on the Caterpillar Electronic Technician (ET). The relay is normally deactivated. The output activates the relay. The ECM allows the heating element to operate for a programmed period of time. The ECM periodically activates the output for heater control.Documentación
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System Operation for the Electrical Heating Element
Illustration 12 Schematic diagram for the electric heating element The dashed lines indicate the wiring that is provided by the Original Equipment Manufacturer (OEM). The heating element is off.com/sisweb/sisweb/techdoc/techdoc_print_page.. 30/05/2011
. the ECM deactivates the output. The relay contains no moving parts.
https://sis. Note: The spark is automatically enabled if the spark has been disabled via Cat ET and power is cycled to the ECM. The relay does not make a clicking noise when the relay is activated and deactivated. Then.

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Illustration 15 Components for the ignition system (46) Ignition wire
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(47) Ground wire between the engine block and the ARD head (50) Ground point on the ARD head (51) Spark plug
Illustration 16 Typical ARD head (51) Spark plug (52) Spark plug's electrode (53) Ground probe
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Primary Ignition Circuit The primary ignition circuit consists of the ECM.cat. or on top of the valve cover. 30/05/2011
.. and the wiring between the ECM and the ignition coil.C15 On-highway Engine SDP00001-UP(SEBP4419 . above the exhaust manifold. The ECM creates an ignition pulse signal. Secondary Ignition Circuit The secondary ignition circuit consists of the following components: • Ignition coil (48)
https://sis. The ignition coil may be located near the oil filter.com/sisweb/sisweb/techdoc/techdoc_print_page. ignition coil (7). The signal is sent to the primary ignition coil.jsp?returnurl=/sisweb/s.

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. One ground point (50) is on the ARD head. The coolant is used to extend the life of the O-ring for the ARD nozzle.
Turbochargers
Illustration 17 Turbochargers
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Coolant
Two lines circulate coolant in the ARD head.cat. Ignition wire (46) connects the ignition coil's output to spark plug (51). One ground point (45) is on the engine block near the ignition transformer. The spark ignites the air/fuel mixture. The spark jumps between the spark plug's electrode (52) and ground probe (53). The ground wire runs inside the insulation (44) that is wrapped around ignition wire (46).. The ground wire is connected to two ground points.Documentación
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• Ignition wire (46) • Spark plug (51) • Ground wire (47) Ignition coil (48) converts the ignition pulse signal into a high voltage signal.com/sisweb/sisweb/techdoc/techdoc_print_page. Ground wire (47) ensures that the secondary ignition circuit is complete between the ARD head and the ignition coil.

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Illustration 18 Typical example of a turbocharger (57) Air inlet (58) Compressor housing (59) Compressor wheel (60) Bearing (61) Oil inlet port (62) Bearing
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https://sis. The exhaust gas from the low pressure turbocharger is fed into the vehicle's exhaust system.Documentación
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(54) Wastegate (55) High pressure turbocharger (56) Low pressure turbocharger
High pressure turbocharger (55) is mounted to the exhaust manifold of the engine.cat.. Low pressure turbocharger (56) is located below the high pressure turbocharger on the engine. 30/05/2011
.com/sisweb/sisweb/techdoc/techdoc_print_page.39) .C15 On-highway Engine SDP00001-UP(SEBP4419 .. Wastegate (54) is used in order to control the amount of exhaust gas that enters the turbocharger's turbine during engine acceleration.

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(63) Turbine housing (64) Turbine wheel (65) Exhaust outlet (66) Oil outlet port (67) Exhaust inlet
The exhaust gas from the engine enters the turbocharger's turbine housing (63) through exhaust inlet (67). This compression allows a larger amount of air to enter the engine.
Illustration 19 Turbocharger with wastegate (68) Canister (69) Actuating lever
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https://sis..C15 On-highway Engine SDP00001-UP(SEBP4419 .. The engine produces more power because the engine is able to burn additional fuel with greater efficiency. The overall effect is an increase in power. The action of the compressor wheel blades causes a compression of the inlet air.com/sisweb/sisweb/techdoc/techdoc_print_page.39) . More exhaust gases cause the turbine wheel and the compressor wheel to turn faster. The blades of the turbocharger's turbine wheel (64) are caused to rotate. additional fuel is injected into the cylinders. With more air in the engine. As the turbine rotates. the exhaust gas flows around the turbine and exits through the turbocharger's exhaust outlet (65). The increased engine speed creates more exhaust gases. the engine is able to operate more efficiently. When the load on the engine increases or when a greater engine speed is desired. The rotation of the compressor wheel pulls clean air through air inlet (57) of compressor housing (58). The increased flow of air allows the engine to produce more power. the turbine wheel and the compressor wheel are caused to rotate at very high speeds.jsp?returnurl=/sisweb/s. Because the turbocharger's turbine wheel is connected by a shaft to the turbocharger's compressor wheel (59).cat. Additional air is forced into the engine as the compressor wheel turns faster. 30/05/2011
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Note: The calibration of the wastegate is preset at the factory.C15 On-highway Engine SDP00001-UP(SEBP4419 . This moves actuating lever (69).jsp?returnurl=/sisweb/s..cat.. Under conditions of high boost. the wastegate is opened. The lubrication oil for the bearings flows through oil inlet port (61) and into the oil cavity in the center section of the turbocharger cartridge. The oil exits the turbocharger through oil outlet port (66). No adjustment can be made to the wastegate. Under low boost. 30/05/2011
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The engine does not operate efficiently under conditions of low boost. The rpm of the turbocharger is limited by bypassing a portion of the exhaust gases around the turbine wheel of the turbocharger. Low boost is a condition that occurs when the turbocharger produces less than optimum boost pressure.39) . the wastegate opens. The actuating lever closes the wastegate.com/sisweb/sisweb/techdoc/techdoc_print_page. The open wastegate allows exhaust gases to bypass the turbine side of the turbocharger. There is a spring that is located inside canister (68). The oil then returns to the engine oil pan through the oil drain line for the turbocharger. the spring pushes on the diaphragm within the canister. When the boost pressure increases against the diaphragm that is in the canister. Bearing (60) and bearing (62) in the turbocharger use engine oil that is under pressure for lubrication. which will allow the turbocharger to operate at maximum performance.
Valves And Valve Mechanism
Illustration 20 Valve system components
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The follower is used in order to transfer the lift that is machined into the camshaft lobe to rocker arm (65) . Valve adjustment screw (71) is used in order to adjust the valve lash. One camshaft lobe operates both of the inlet valves for each cylinder. Valve springs (77) are used to hold the valves in the closed position when lift is not being transfered from the camshaft lobe.
https://sis. The camshaft must be timed to the crankshaft in order to get the correct relation between the piston position and the valve position.. This applies the lifting action to valve bridge (75). the rocker arm pivots at rocker shaft (72).cat.Documentación
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(70) Rocker arm (71) Valve adjustment screw (72) Rocker arm shaft (73) Camshaft follower (74) Camshaft (75) Valve bridge (76) Valve rotator (77) Valve spring (78) Valve (79) Valve seat
The valve train controls the flow of inlet air into the cylinders and the flow of exhaust gases out of the cylinders during engine operation. The camshaft lobe lifts the camshaft follower of the rocker arm. Each cylinder has two inlet valves and two exhaust valves. There is also one camshaft lobe that operates the unit injector for each cylinder. Specifically machined lobes on camshaft (74) are used in order to control the following aspects of valve function: • Height of valve lift • Timing of valve lift • Duration of valve lift The crankshaft gear drives the camshaft gear through the front gear train. The rotation of the valves in the valve seat prevents valve damage by constantly changing the contact area of the valve face and valve seat (79). The camshaft has three camshaft lobes for each cylinder.. As the camshaft lobe lifts the follower.jsp?returnurl=/sisweb/s. 30/05/2011
. Camshaft follower (73) rolls against the surface of the camshaft lobe. The springs provide the force on the valve in order to ensure that the valves will close at high rpm. This actuates valve (78). This rotation gives the valves longer service life. The valve bridge is used to transfer the lift from the rocker arm to the valves.com/sisweb/sisweb/techdoc/techdoc_print_page.C15 On-highway Engine SDP00001-UP(SEBP4419 . Valve rotators (76) cause the valves to rotate while the engine is running. The springs also ensure that the valves will remain closed under conditions of high boost pressures. One camshaft lobe operates both of the exhaust valves for each cylinder.39) .

Actuator (90) . Adjustable idler gear (82) is driven by idler gear (83). The spool is normally closed. The components that change are the cylinder head and the head gasket. The inlet valves and the exhaust valves are also closed by the valve mechanism. The cluster gear is driven by crankshaft gear (86). Control Valve (87) . For information on setting the timing gear backlash.com/sisweb/sisweb/techdoc/techdoc_print_page.
https://sis.C15 On-highway Engine SDP00001-UP(SEBP4419 . Pressurized engine oil flows from the rail to each actuator. This eliminates vibration and noise. Pressure Sensor (88) . The oil is released into the space underneath the valve cover and the rail pressure is reduced. 30/05/2011
. The system is controlled by the Engine Control Module (ECM). If the cylinder head is removed. The system contains the following components: Check Valve (89) .Documentación
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(85) Cluster gear (86) Crankshaft gear
The inlet valves and the exhaust valves are opened by the valve mechanism. tolerances of the components will change.Pressurized engine oil flows to a rail inside the valve cover base. A check valve prevents oil from flowing from the rail back to the main oil gallery. The ECM monitors the signal in order to determine the pressure of the oil in the rail. The control valve contains a coil and a cartridge assembly..Time".cat. Timing mark (84) and timing mark (80) are aligned in order to provide the correct relationship between the piston and the valve movement.39) . When the spool is closed. The cartridge assembly contains a spool. The actuators use the pressurized engine oil and electrical commands from the ECM in order to delay the closing of the intake valves. The engine also runs smoother at all operating speeds.
Variable Valve Actuator
The Intake Valve Actuation system (IVA) uses pressurized engine oil to delay the closing of the intake valves.The actuators are located under the valve covers. The sensor converts the rail pressure into an electrical signal.A control valve is threaded into the rail. refer to Testing and Adjusting.. The ECM sends a signal to the coil in order to fully open the spool. These thrust rollers are designed to counteract the torsional forces from the injector pulses. Camshaft gear (81) is driven by a series of two idler gears. This occurs as the rotation of the crankshaft causes a relative rotation of the camshaft.jsp?returnurl=/sisweb/s.A pressure sensor is threaded into the rail. This idler gear is driven by cluster gear (85). The adjustable idler gear must be relocated in order to maintain the correct backlash setting. the oil is contained in the rail. The camshaft drive gear has integral pendulum rollers that act as a vibration damper for the front gear group. The backlash adjustment is made between the idler gear and camshaft gear. The adjustable idler gear is designed to be adjusted so that backlash can be adjusted for the front gear train. "Gear Group (Front) .

• The ECM checks the temperature of the coolant. The ECM samples the rail pressure. The ECM activates a code if the pressure difference is too low.Documentación
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(88) Pressure sensor (89) Check valve (90) Actuators
System Operation During Engine Start The ECM performs the following sequence of operations when the engine is started: • The ECM commands the control valve to open for 17 seconds. The ECM compares the two pressure values.
https://sis..jsp?returnurl=/sisweb/s. • The control valve should remain closed during engine operation. The ECM commands the control valve to close. This allows the temperature of the oil in the rail to warm up. The ECM takes a second sample of the rail pressure.. 30/05/2011
.C15 On-highway Engine SDP00001-UP(SEBP4419 . System Operation During Engine Operation The system does not operate until the engine has reached normal operating temperature.39) . • The ECM commands the control valve to close when the coolant temperature exceeds 20 °C (68 °F).com/sisweb/sisweb/techdoc/techdoc_print_page.cat. • The ECM commands the control valve to open.